Not Applicable
1. Field of the Invention
This invention is in the field of apparatus used to remove an anchoring device, such as a packer, from a well, when the anchoring device has been anchored in place between the production tubing and the casing.
2. Background Art
When an oil or gas well is drilled, it is common to insert a casing into the well bore to maintain the well bore and to provide numerous options for modifying the well bore and producing oil or gas from downhole formations. A production tube, usually composed of threaded steel tubular members, is then typically lowered into the casing to deliver fluids from the well. At various depths, one or more packer assemblies are often installed between the production tubing and the casing, to seal off the annular space between the production tubing and the casing. This allows production of oil or gas fluids from different formations at various depths, which are separated by these packer assemblies.
Packer assemblies usually have one or more elastomeric elements which are expanded radially outwardly, to forcefully contact the casing, to create a liquid tight seal between the production tubing and the casing. Further, packer assemblies usually have one or more slip assemblies which expand radially outwardly, to forcefully contact the casing, to mechanically hold the packer assembly in place relative to the casing. The slip assemblies are usually segmented metallic members with multiple teeth on their outwardly facing surfaces. The expansion mechanisms, including the elastomeric elements and the slip assemblies, are often expanded radially by the longitudinal movement of a setting mechanism, which often includes a hydraulically driven piston. The piston can act against a ramp contour, for example, to convert the longitudinal motion of the piston to the outward radial motion required to expand the expansion mechanisms.
Anchoring devices other than packer assemblies may have only slip assemblies and no sealing elements. Where the terms packer or packer assembly are used in this application, it should be understood that reference is also made to nonsealing types of anchoring devices, where the language permits.
Since the packer assembly is usually mechanically attached to the production tubing, such as by threaded connections, anchoring the packer in the casing also fixes the production tubing in place in the casing. Therefore, if it becomes necessary to remove the production tubing, it is necessary to remove the packer assemblies, either separately or along with the production tubing. It can also sometimes be desirable to release a packer assembly and leave it in place. It is common to provide a means of releasing a packer assembly, by adapting the setting mechanism to be released in some way, such as by relieving the hydraulic pressure on a piston to allow the piston to retract, or by forcefully retracting the piston. Others are designed to enable the releasing of the packer by rotation of an operating element, or by other means. A packer assembly which has been designed to release is often referred to as a xe2x80x9cretrievablexe2x80x9d packer, since it can be easily released and retrieved.
Other packer assemblies are not designed to be easily released, either for economic or operational reasons. That is, when the setting mechanism has been set, the packer will remain set, with no built-in provision for releasing the setting mechanism. This is sometimes accomplished by using detent mechanisms or other locking mechanisms to lock the setting mechanism in place. It would be desirable to have a method and apparatus for releasing and retrieving an anchoring device that may not have been designed as a retrievable device.
The present invention includes a method and apparatus for releasing and retrieving from a well bore a packer assembly, or other anchoring device, which may otherwise be designed and implemented as a non-retrievable assembly. More specifically, the packer assembly is designed to expand and set its expansion mechanism by generating a longitudinal force which is converted into an outward radial force on the expansion mechanism. Once set, the setting mechanism is locked into place by a snap ring, detent mechanism, or some other locking mechanism.
A locator profile is included in the design and installation of the packer assembly, with the locator profile being utilized to precisely longitudinally locate a cutting tool which can later be lowered into the well, if it becomes necessary to release and retrieve the packer. A locator element is included in the design of the cutting tool, with the locator element being designed to land in, and in some cases latch into, the locator profile on the packer assembly. The cutting tool has either a cutting blade or another type of cutting element, such as a chemical cutter, laser, or torch. The distance between the locator element and the cutting element, on the cutting tool, is selected to precisely place the cutting element at a position where the body mandrel can be safely cut, once the cutter locator element has landed in the cutter locator profile.
Where the term body mandrel is used in this application, it should be understood that it is not intended to be limited to a specific type of member, except as the function of the body mandrel is described herein, relative to the operation of the packer assembly or other anchoring device.
The cutting element cuts through the body mandrel at the selected location. The depth of the cut is also precisely controlled to allow the cutting element to penetrate the body mandrel without penetrating the remainder of the packer assembly. This allows the ends of the packer assembly to move apart, to retract the setting mechanism, assisted if necessary by subsequent lifting on the packer assembly; it also allows the entire packer assembly and its tailpipe to be pulled from the well. A stop member is provided on the body mandrel for limiting the extent to which the anchor device can be pulled apart, to provide support for pulling the device out of the hole.
In one embodiment, the locator profile can include either an internal shoulder, or some other internal restriction, in a landing sub mounted to the production tubing. This shoulder can be located either above or below the packer. The cutting tool can include an external collar as a locator element, with the collar being designed to land on the shoulder for precise longitudinal positioning of the cutting element. In this embodiment, the upper end of the anchoring device or packer assembly is left attached to the production tubing. The cutting tool can be lowered through the production tubing, on either wireline or coil tubing, to cut through the body mandrel and release the packer. The packer can then be pulled out of the well, along with its tailpipe, by pulling the production tubing. In this embodiment, a chemical cutting element, torch, or laser can be lowered on either a wireline or coil tubing. A cutting tool having a blade can be lowered on coil tubing, with the blade being rotated by a downhole motor.
In another embodiment, the locator profile can be in a connector on the top of the packer assembly or anchoring device. This can be a removable seal bore, a threaded connector, or any other type of connector that may be present on the top of the anchoring device. The cutting tool can include a connector on its lower end, such as a latching mechanism, with the connector on the lower end of the cutting tool being designed to land on, and latch to, the connector on the upper end of the packer assembly, for precise longitudinal positioning of the cutting element. In this embodiment, the upper end of the packer assembly is first disconnected from the production tubing, and the production tubing above the packer is removed from the hole. The upper end of the packer assembly can then be prepared for connection to the cutting tool, if necessary, such as by removal of a seal bore. The cutting tool can be lowered through the casing, on a threaded tubular workstring, to land the connector on the lower end of the cutting tool in the connector on the upper end of the packer assembly. Once the cutting tool has been attached to the upper end of the packer assembly, the workstring can be rotated, if required to rotate the cutting element, to cut through the body mandrel and release the packer. The packer can then be pulled out of the well, along with its tailpipe, by pulling the workstring. In this embodiment, the cutting element can be either a blade, a chemical cutter, a torch, a laser, or some other type of cutting element. Similarly, as an alternative to rotating the workstring, a downhole motor can be used to rotate the blade or other cutting element.
The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which: